Monday , August 10 2020
7th Class CBSE Science NCERT Book

Reproduction in Plants: 7 NCERT CBSE Science Chapter 12

Reproduction in Plants 7th Class NCERT CBSE Science Chapter 12

Question: Why is the process of reproduction necessary?

Answer: The process of reproduction is necessary for the perpetuation and preservation of species and to increase the number of members of species.

Question: If the filament of Spirogyra is broken into fragments. What will you observe?

Answer: If the filament of Spirogyra are broken into fragments, then each fragment will develop into a new plant.

Question: Fungus, moss and fern reproduce by a common method of asexual reproduction. Name the method.

Answer: Fungus, moss and fern reproduce by the common method of spore formation which is a type of asexual reproduction.

Reproduction in Plants NCERT – Question: A flower consists of different parts. Name these parts of a flower.

Answer: The four main parts of a flower are

  1. Sepals
  2. Petals
  3. Stamen
  4. Pistil

Question: Mention the mode of reproduction in the following plants

  1. Spirogyra
  2. Yeast
  3. Money plants

Answer:

  1. Spirogyra – fragmentation
  2. Yeast – budding
  3. Money plant – Vegetative propagation

Question: Pick the odd one out from the following on the basis of mode of reproduction and give reason for it, Sugarcane, Potato, Rice, Rose.

Answer: The odd one out is rice.

In the above given pairs as rice reproduces by sexual reproduction and sugarcane, potato and rose reproduces vegetatively.

Question: Give one difference between unisexual and bisexual flower.

Answer: Unisexual flowers are those which contain either male or female reproductive part and bisexual flower has both reproductive parts (i.e. male and female) on the same flower.

Question: Flowers are colorful and fragrant. Give reason supporting the statement.

Answer: Flowers are so colorful because they absorb and reflect light energy. Fragrance results from production of volatile chemicals which evaporate.

Question: Boojho had the following parts of a rose plant-a leaf, roots, a branch, a flower, a bud and pollen grains. Which of them can be used to grow a new rose plant?

Answer: Branch can be used to grow a new rose plant. As, rose reproduces by vegetative propagation, i.e. stem cutting method.

Question: Formation of new but similar individuals from parents is characteristic feature of which process?

Answer: Reproduction is the process of production of new similar organisms from their parents.

Question: Name two plants where vegetative reproduction takes place by roots.

Answer: Sweet potato and dahlia develops new plants through their roots by the process of vegetative reproduction.

Question: A yellow powdery substance is present in the anther which participates in reproduction process. Name this substance.

Answer: Pollen grains

Reproduction in Plants NCERT – Question: In which part of flower does fertilization occur?

Answer: Ovary is the part where male and female gametes fuse together.

Question: Bryophyllum leaves reproduce using which mode of reproduction?

Answer: Asexually by vegetative propagation.

Question: What are the bulb-like projections forming in yeasts?

Answer: The bulb-like projections formed during reproduction are called buds.

Question: ‘Spores’ as a means of asexual reproduction are used by which plants?

Answer: Spores are produced by fungi, ferns and mosses during unfavorable conditions.

Question: Write the male and female reproductive parts present on the flowers.

Answer: The male reproductive part is stamen and the female reproductive part is pistil.

Question: Pollen grains are present inside anthers for long time yet they do not die. Why?

Answer: Pollen grains have a tough protective coat which presents them from drying up.

Question: Name two plants in which pollination occurs by water.

Answer: Vallisneria and Hydrilla.

Question: Fruit is the ripened ovary of a flower. Explain.

Answer: After fertilization, the ovary of a flower develops and becomes a fruit with seeds present inside.

Question: Banana is a fruit without seeds. Give reason.

Answer: Banana forms from one parent only. There is no seed production.

Short Answer Type QuestionsReproduction in Plants NCERT

Question: When you keep food items like bread and fruits outside for a long time especially during the rainy season, you will observe a cottony growth on them.

  1. What is this growth called?
  2. How does the growth take place?

Answer:

  1. When food items like bread and fruits are kept outside for a long time especially during rainy season, a cottony growth of bread mould, a fungus is observed.
  2. This growth of fungus takes place by spores present in air, which when comes in the contact with moisture in bread germinates and grow to produce new cells.

Question: Collect some flower of different plants like papaya, rose, mustard, lady’s finger, Petunia, cucumber, corn, pea, etc. Group them under following heads.

  1. Which of these plants have unisexual flowers?
  2. Which of these plants have bisexual flower?
  3. What is the other name of unisexual and bisexual flower?

Answer:

  1. Unisexual flowers are papaya, cucumber, com.
  2. Bisexual flowers are rose, mustard, lady’s finger, Petunia, pea.
  3. Unisexual flowers are also called as incomplete flower while bisexual flowers are called hermaphrodite or complete flowers.

Question: Coconut is a large and heavy fruit. How is it adapted for dispersal by water?

Answer: The seeds of some plants that have an outer fibrous or spongy covering are dispersed through water. They have the ability to float in the water and drift along with its flow, e.g. seeds of water lily, lotus, chestnut (singhara) and coconut are dispersed through water. The coconut fruits have a fibrous outer coat which enables them to float in water and carried away by flowing water to far off places.

Question: What is a bud? Which organism reproduce by budding? Given the diagrammatic representation of budding in a plant.

Answer: Buds are small bulb-like projections of yeast cell.
These are asexual reproducing bodies of yeast.
Diagrammatic representation of budding in yeast Refer to figure on page 178.

Question: Group the seeds given in figure (i) to (iii) according to their means of dispersion.

  1. Seed dispersed by wind.
  2. Seed dispersed by water.
  3. Seed dispersed by animal.

Answer:
The seeds and their means of dispersal can be given as follows:

  1. The seed of maple is dispersed by wind. It has winged seed which are light in weight.

    Seeds of (a) drumstick and (b) maple
  2. Seed of aak or madar has hairy outgrowth which makes it lighter and can be dispersed by wind.
    (a) The hairy fruit of sunflower and (b) hairy seed of madar (aak)
  3. Seed of Xanthium have numerous spines on them which gets attached to the fur of animals. Hence, these are dispersed by animals.

    Xanthium

None of the seed given in the figure is dispersed by water

Question: How does male gamete present in pollen grain reaches female gamete present in ovule?

Answer: After pollination, the pollen grains fall on the surface of stigma and germinate to form a long tube, reaching the ovules inside the ovary, the egg or female gamete is present in the ovule.

The outer surface of pollen grains rupture and male gametes are released to fuse with egg.

Question: How do the plants like sugarcane, potato and rose reproduce when they cannot produce seeds?

Answer: Sugarcane and rose are propagated by stem cutting that is a method of vegetative propagation, in which stem is capable of growing into a mature independent plants that are identical to their parents.

Potato is an underground modified stem having bud called eyes, which sprout and develop into a new identical plant.
Thus, the plants which cannot produce seeds, can be propagated vegetatively with the help of vegetative parts such as stem, roots, buds and leaves.

Question: Mention the benefits of seed dispersal.

Answer: Benefits of Seed Dispersal

  1. Seed dispersal avoids overcrowding of young plants around their parent plants.
  2. It helps in preventing competition between the plants and its own seedlings for sunlight, water and minerals.
  3. One of the benefits of seed dispersal is that it enables the plant to grow into new habitats for wider distribution and provides them with better chance of survival.

Question: What is meant by the term fertilization? List the step wise manner leading to formation of an embryo.

Answer:


Fertilization (Zygote formation)

The process in which the male gamete fuses with female gamete to form a new cell (called zygote) is called fertilization.

When the pollen are deposited on the stigma of the pistil, it begins to germinate. After sometime, a long pollen tube is developed from the pollen grain which passes through the style towards the female gametes in the ovary. The male gametes move down the pollen tube and the tube enters the ovule present inside the ovary.

The tip of pollen tube bursts and the male gamete comes out of the pollen tube. Inside the ovary, the male gametes fuse with the female gametes present in the ovule to form a fertilized egg cell which is called zygote. The zygote develops into an embryo which is a part of a seed that develops into a new plant.

Question: A student was given a flower. He was asked to pick the different whorls of flower by the forcep. He pulled each part of the flower and laid them on the chart paper in a sequence and named them W, X, Y, Z (from outer to inner whorl). He was unable to name them.

Help the student to name the different parts of a flower. Also help him to tell which part produces male gamete and female gametes.

Answer: The four whorls of the flower are outermost whorl ‘W’ is green part which is called sepal. Inside sepal the next whorl is X which is colored and attractive part of the flower called petals. The Y is the inner whorl of flower called stamen. It is the male reproductive part of flower. It consist of two parts, i.e. anther and filament. The anther contains male gametes called pollen grain. The whorl ‘Z’ is the innermost part of the flower called pistil. It is the female reproductive part of flower. It consist of three parts, i.e. stigma, style and ovary. The ovary produces ovule which contains the female gametes or egg cell.

Question: One morning as Paheli strolled in her garden she noticed many small plants, which were not there a week ago. She wondered, where they had come from as nobody had planted them there. Explain the reason for the growth of these plants.

Answer: The small plants which were not there in the garden a weak ago have grown up due to seed dispersal. The seeds from the tree may have fallen below or have been dispersed by wind or animals on the ground, which on germination developed into new small plants.

Question: Place a piece of bread in a moist and warm place for few days. Observe it after few days. What will you see?

  1. Name the organism that grows on the bread piece?
  2. What are the thread-like projections called?
  3. What is the knob like structure present on the top of thin stem called?
  4. Which type of reproduction does this organism shows?
  5. From where does the spors comes to the bread piece?

Answer:

  1. When the bread piece is kept in a moist and warm place for few days, bread mould grows on the bread piece.
  2. The thread-like projections are called hyphae or mycelium.
  3. The thin stem having knob-like structure on the top is called sporangia or sporangium which contains hundred of minute spores.
  4. Bread mould shows asexual mode of reproduction.
  5. These spores are present in the air and when favorable conditions arrive, the grow into new plants.

Question: Write how the following seeds are dispersed.

  1. Seeds with wings
  2. Small and light seeds.
  3. Seeds with spines / hooks.

Answer: The mode of dispersal of the seeds having following properties are as follows:

  1. Seeds with wings-like seeds of drumstick and maple become light weighted and can be blown away by air. Thus, these are dispersed by wind.
  2. Small and light seeds like seeds of grasses and cotton (having hairy growth) are also dispersed through wind.
  3. Seeds of Xanthium, Urena have spines and hooks on them, these hooks or spines are attached to the fur of the animal body. When animals move to other places and rub their body with tree, etc., these seeds fall from their body and get dispersed.. Therefore, these are dispersed through animals.

Question: Why is vegetative propagation a preferred method of asexual reproduction?

Answer: The following advantages of vegetative reproduction makes it a preferred method

  1. It takes less time to grow and bear flower and fruits than those produced from seeds.
  2. The new plants are the exact copies of parent plant because they are produced from a single parent.

Question: Insects are called agents of pollination. How do they aid in process of pollination?

Answer: Flowers have nectar that attract insects. Insects suck these nectar as their food. When insects like bee, butterfly, etc., sit on the flower for sucking nectar, the sticky pollen grains get attached to their legs and wings. When these insects again sit on another flower, these pollen grains are transferred to the stigma of that flower from the body of the insects. In this way, insects help in pollination.

Question: What is seed dispersal? What will happen if all the seeds of a plant were to fall at a same place and grow?

Answer: Plant produces large number of seeds. When these seeds fall down they starts growing. The process by which the seeds are scattered to different place (far and wide from their parents) is called seed dispersal.

The seeds and fruits are dispersed away through various agencies like air, water and animals. Sometimes dispersal takes place by the explosion or bursting of fruits. If all the seeds of a plant were to fall at the same place and grow, there will be a severe competition for sunlight, water, mineral and space. As a result, the survival for the plants will be difficult and the plants who survive will not grow into a healthy plants.

Question: Describe the structure of a flower.

Answer: The main parts of a flower are:


Reproductive parts

  1. Sepals These are the green leaf-like outermost circle of the flower. All the sepals are together referred to as calyx. The function of calyx is to protect the flower when it is in bud form.
  2. Petals These are the colorful and most attractive part of flower. These lie inside the sepals. All the petals are together referred to as corolla. These are scented and attract insects for pollination.
  3. Stamen It is a male reproductive organ of plant. These are the little stalks with swollen top and lies inside the ring of petals. The stamen is made up of two parts, i.e. filament and anther. The stalk of stamen is called filament and the swollen top of stamen is called anther.
    Anther contains the pollen grain which have male gamete in it. Pollen grains are exposed when the anther ripens and splits. These appear as the yellow powder like substance which is sticky in nature. Flowers usually have a number of stamens in it.
  4. Pistil It is the female reproductive part of a flower that lies in the center of a flower. These are flask-shaped structure which is made up of three parts, i.e. stigma, style and ovary.
    The top part of pistil is called stigma. It receives the pollen grains from the anther during pollination. The middle part of the pistil is tube-like structure called style which connects stigma to the ovary.
    The swollen bottom part at the base of pistil is called ovary.
    The ovary makes ovules and stores them. These ovules contain the female sex cells also called as egg cell. It is the female gamete of flower. Pistil is also called as carpel. The pistil is surrounded by several stamens.

The base of the flower on which all the parts of flower are attached is called receptacle.

Question: Observe the given figure?

  1. Which plant is this? Give the name of the plant.
  2. What does it shows?
  3. From where the new plants are developing?

Answer:

  1. The given figure is of Bryophyllum leaf. It is also called as sprout leaf plant.
  2. It shows vegetative reproduction by leaves.
  3. The leaves of Bryophyllum develops some buds in its margin or edges which grow into new plants, when buried in the soil.

Question: The process of layering is commonly used in jasmine for reproduction. Explain how this process of layering is performed in jasmine.

Answer: Layering is a method of vegetative reproduction in branches. In this method, a mature branch of parent plant is bent down and covered with soil.

The tip of the branch is kept above the ground. After few days the roots are developed from the branch buried under the soil and develops into a new plant. This method is done in the plants that have long and slender branches, e.g. jasmine.

Long Answer Type Questions:

Question: In the figure of a flower given below, label the parts whose functions are given below and give their names.

  1. The part which contains pollen grains.
  2. The part where the female gamete is formed.
  3. The female reproductive part, where pollen grains germinate.
  4. The colorful part of flower which attracts insects

Answer: The various parts of a flower whose functions are mentioned above are labelled as follows:


Pollination in flower

Question: Explain the process of reproduction in plants, involving the fusion of cells from male and female parts of a flower.

Answer: When the reproduction in an organism includes two types of gametes, i.e male and female from two different parents, it is called sexual reproduction. The sexual reproduction takes place by the fusion of male and female gametes by the process called fertilization to form zygote.


Fertilisation (Zygote formation)

Sexual reproduction (fertilization) in plants The different steps that take place during sexual reproduction in plants are

  1. The pollen are deposited on stigma and begins to germinate.
  2. Pollen tube containing male gametes reaches to the ovary of flower.
  3. The tip of the pollen tubes gets dissolved and male gametes comes out of the pollen tube.
  4. Inside the ovary male gametes fuse with the female gamete or egg present in the ovule.
  5. The fusion of both the gametes will result into a fertilized egg cell which is also called as zygote.

Question: Name some fruit bearing plants. Now make a table and describe the method of seed dispersal in these fruits as well as the part which helps in the seed dispersal.

Answer: The method of seed dispersal in the fruits and the parts which help in the seed dispersal:
Name of fruits bearing plants Agents through which seeds are dispersed Parts or seeds which helps in dispersal

Name of fruits bearing plants Agents through which seeds are dispersed Parts or seeds which helps in dispersal
Drumstick Air / wind Winged seeds
Sunflower Wind Hairy seeds
Gokhru Animal Spines and Hooks
Coconut Water Fibrous coating
Lotus Water Thalamus float in water
Poppy Explosion Pericarp bursts
Grass Wind minute, light weighted seeds

Question: Observe the given figure and answer the following questions.

  1. Name the plant?
  2. Which type of reproduction is seen in this plant?
  3. Is ginger a root or stem?

Answer:

  1. The given figure is of ginger tuber.
  2. Asexual reproduction is seen in this plant.
  3. Ginger is a stem.

Question: Ria went to a plant nursery with her mother. The gardener approached them and asked about their choice of plant. Ria’s mother wanted a flowering plant with fragrance. Gardner showed them a plant and told them that this variety has been prepared by a method of vegetative propagation of stems.

Ria grew curious and asked some questions to gardener.

  1. What is vegetative propagation?
  2. What are methods of producing new plants using stem?
  3. Name any two plants where this method of reproduction is used. Is this a asexual or sexual method?
  4. What values do you observe in Ria?

Answer:

  1. Vegetative propagation is the process of reproduction in which new plants are produced from different parts of old plants like stem, roots or leaves.
  2. Cutting and grafting method are two methods where stem is used for vegetative propagation.
  3. Mango and rose are two plants cultivated using vegetative propagation.
    This is an asexual method of reproduction.
  4. Ria is curious, inquiring who wants to gain knowledge about process occurring around here.

Question: Ravi was sitting in a garden with his family. His younger sister comes running with different types of flowers and starts to name their parts. She stops as she forgets some names and Ravi noticing this comes to help her.

His sister asks many questions related to flowers and Ravi answers her with all information he has.

  1. What is a flower and mention its function during reproduction?
  2. Flowers help in pollination and fertilization. Yes/No? Give reason.
  3. Do all flowers have both male and female parts on them specify?
  4. What values are observed in Ravi and his sister?

Answer:

  1. A flower is the reproductive part of plant which helps in sexual reproduction.
    A flower ensures the occurrence of process of fertilization.
  2. Yes, flower aids in both pollination and fertilization. Different colors and fragrance of flowers attract insects to them causing dispersal of pollen grain ensuring pollination.
    Fertilization occurs in the ovary of the flower after pollination of male and female parts.
  3. Number of some flowers can either have male or female parts on them, these flowers are called unisexual.
    Some flowers have both, the male and female parts on them so they are called bisexual flowers.
  4. Ravi is aware, sincere, helpful as he helps others and knowledgeable while his sister is inquisitive, ready to acquire new knowledge and observant.

Fill in the Blanks

  1. The male and female gametes fuse to form a …………… during the process of …………… This grows into an …………… which is enclosed within a seed. After fertilization the ovules develop into …………… and the ovary develops into a ……………
  2. Roots, stems and leaves are called …………… of a plant.
  3. The small bulb like projections coming out from the yeast cell is called a …………… .
  4. The scars present on the potato tubers are called …………… .
  5. Spirogyra\s an alga which may breaks up into two or more …………… .
  6. The …………… is the male reproductive part of flower while …………… is the female reproductive part of a flower.
  7. Pollen grains are …………… that can be carried by …………… or …………… .
  8. The cells which result after …………… of the gametes is called …………… .

Answers:

  1. zygote, fertilization, embryo, seed, fruit
  2. vegetative part
  3. bud
  4. eye
  5. fragments
  6. stamen, pistil
  7. light, wind, water
  8. fusion, zygote

True / False

  1. Potato reproduces from seeds.
  2. Hibiscus or China rose is a bisexual flower.
  3. Jasmine is grown by grafting.
  4. Asexual reproduction in yeast takes place by budding.
  5. Pollination is the process of fusion of male and female gametes.
  6. Fruits are developed from the ripened ovary.
  7. Pollen grains are present in anther.
  8. Maple seed is dispersed by explosion mechanism.
  9. Two individuals are needed for the sexual reproduction.
  10. Pistil is the male reproductive part of a flower.

Answers:

  1. False, potato reproduces from ‘eyes’ which are buds present on its body.
  2. True
  3. False, jasmine is grown by layering method of vegetative propagation.
  4. True
  5. False, pollination is the process of transfer of pollen grains from anther to the stigma of flower.
  6. True
  7. True
  8. False, maple seed is dispersed by wind or water as these seeds are very light and hairy.
  9. True
  10. False, pistil is the female reproductive part of a flower.

Question: Match the Column I with Column II

Column I Column II
(a) Sugarcane (i) Jasmine
(b) Grafting (ii) Cutting
(c) Scion (iii) Detached body parts
(d) Bryophyllum (iv) Fragmentation
(e) Layering (v) Vegetative reproduction by roots
(f) Cactus (vi) Spores
(g) Rose (vii) Through stem cutting
(h) Spirogyra (viii) Leaves
(i) Sweet potato (ix) Mango
(i) Bread mould (x) Is the shoot part

Answers:

  1. (a)-(vii)
  2. (b)-(ix)
  3. (c)-(x)
  4. (d)-(viii)
  5. (e)-(i)
  6. (f)-(iii)
  7. (g)-(ii)
  8. (h)-(iv)
  9. (i)-(v)
  10. (j)-(vi)

Check Also

7th Class CBSE Science NCERT Book

Electric Current and its Effects: 7th NCERT CBSE Science

Electric Current and its Effects 7th Class NCERT CBSE Science Chapter 14 Question: Mention the name of …

Leave a Reply

Your email address will not be published. Required fields are marked *